The invention relates to pumps in general, and more particularly to improvements in casings for centrifugal pumps. Still more particularly, the invention relates to improvements in casings for single-stage or multi-stage in-line centrifugal pumps.
German Pat. No. 32 10 526 to Jensen et al. discloses a single-stage in-line pump with a casing which is assembled of two sections. The sections are joined to each other in a plane which includes the axis of the pump shaft. The casing resembles a volute and its sections are not identical, i.e., they are not mirror images of each other. This contributes to the initial cost of the casing because each of the two sections must be shaped in a different tool. The cost of such pumps is especially high if the pumps are to be furnished in different sizes so that a set of two different tools is needed for the making of each of two or more sets of casings having different sizes. The patented pump further comprises a partition which is installed between the two sections cf the casing in such position that its plane is disposed at right angles to the plane in which the two sections are secured to each other. This necessitates the establishment of first connections between the partition and the two sections of the casing, and the establishment of additional connections between the sections. As a rule, the sections are secured to each other in a first step, and the partition is thereupon installed between the assembled sections in a next-following step.
U.S. Pat. No. 3,059,582 to Greene et al. discloses a motor pump unit with a pump casing which is assembled of two sections and further comprises a partition which is installed between the two sections in a separate step following attachment of the sections to each other. This contributes to the cost of the casing.
German Pat. No. 27 07 776 to Le Dall discloses a multi-stage centrifugal pump with an intermediate housing or casing which is made in an injection molding or casting machine and embodies an integral partition. The intermediate casing is further provided with a flange for attachment to the housing of a motor. That side of the casing which is located opposite the flange can be connected to the housing of a first pump stage. The partition of the casing separates a pressure chamber from a suction chamber and is provided with a hole for sealing means surrounding the pump shaft. The casing of Le Dall is complex and expensive. Moreover, such casing must have thick walls if it is to stand the forces which are transmitted when the pump is installed in line with a first pipe which supplies fluid to the inlet and with a second pipe which receives pressurized fluid from the outlet of the casing.